Bus systems, for example, EIA-485 compatible bus systems, are used in automation engineering, for example, for a master unit to control a plurality of slave units.
The master unit controlling the slave units may include emitting what is referred to as a request signal (also referred to as “request”) that the master unit provides with an address indicating the designated slave unit. Moreover, a slave unit can also send a response signal (also referred to as “response”) to the master unit via such a bus system.
Bus systems of this kind can have a daisy-chain configuration, for example, in accordance with which a first slave unit is directly connected to the master unit. The other slave units are connected via the preceding slave units thereof to the master unit. Thus, a chain of serially interconnected slave units is formed, from which the term “daisy chain” is derived.
A signal from the master unit, for example, the request signal, can only be fed to a slave unit via the preceding slave unit(s) thereof; and a signal from the slave unit for the master unit, for example, the response signal, can only be fed to the master unit via the preceding slave unit(s) thereof.
A slave unit can be part of an encoder, for example, and a master unit can be part of a control unit of a machine tool.
Thus, depending on the particular application, it can occur that the slave units are spaced apart by as many as several meters, for one thing, and that as many as several preceding slave units must route a signal that the master unit would like to send to one of the last slave units.
At the same time, it can be necessary that the signal from the master unit preferably reach the designated slave unit without delay, thereby ruling out a time-consuming intermediate processing of the signal to be routed in the respective slave units.
In particular, a slave unit should be able to decode a signal directed thereto in a preferably error-free manner, which can presuppose that the signal is transmitted, preferably without loss of information, from the master unit to the designated slave unit.
Analogous demands can be made for the transmission of signals from a slave unit towards the master unit.